The present invention relates to tubular filter elements of the type filtering a dust-laden airflow by separating out airborne particles during passage of the airflow through a pervious wall of the element.
Common to the filtering art are elongate, tubular filter elements, termed bags in the trade, of air pervious material through which is directed a dust-laden flow of air. Particles are separated from the airstream and collect on bag inner or outer surfaces depending on flow direction. Provision is made in state of the art industrial filters to subject the bags or a filter structure to a periodic, reverse flow of air which dislodges and removes the collected particles to purge the filter. Commonly, bag purging is automatically conducted at timed intervals.
During both normal bag operation as well as during bag purging a pressure drop exists across the bag walls resulting in some lateral displacement of the bag wall. To prevent severe distortion, particularly during bag purging, it has become a recognized practice to fixedly incorporate rigid rings at spaced intervals along a filter bag or element.
With continuing attention to the existing state of the art, after several months of bag operation it is common practice that the bag be removed from the filter baghouse for transfer to a laundering facility. During such bag cleaning the bag is subjected to agitation resulting in bag wear particularly where the bag fabric is in contact with a bag shaping ring. Premature bag wear and resultant replacement results in substantial costs to the filter operator. Undetected bag wear can result in later bag failure requiring shutdown of the filter structure.
While the prior art disclosed the use of filter bag shaping rings, no bag structure is found providing convenient installation and removal of such rings. French Pat. No. 1,585,940 mentions that the rings instead of being sewn to the bag may also be positioned at spaced intervals along a bag by suspending the rings in a wire or chain interconnected manner.